I do not know why we cannot do base trades without vacancies. Friends at other airlines can do exactly that. You just find someone in another base that wants to trade, then post it in the crew room. If someone senior to you wants to take the base trade, then they can. I know there is all this talk about circumventing seniority, but if you do something like this then it does not matter, and everyone is happy in a time of little/no movement.

Maybe it is just too simplistic?

Edit: Of course you would have to stay in your equipment/seat.